Chip-on-chip power card with embedded thermal conductor

ABSTRACT

Methods, systems, and apparatuses for a power card for use in a vehicle. The power card includes an N lead frame and a P lead frame, each having a body portion and a terminal portion. The power card includes an O lead frame having a body portion and a cooling portion. The power card includes a first power device located between the body portion of the N lead frame and the body portion of the O lead frame. The power card includes a second power device located between the body portion of the O lead frame and the body portion of the P lead frame, the O lead frame configured to receive heat from the first power device and the second power device by the body portion of the O lead frame and transfer the heat to the cooling portion of the O lead frame for heat dissipation.

BACKGROUND 1. Field

This specification relates to a compact low inductance chip-on-chippower card and method of manufacturing the same.

2. Description of the Related Art

Modern vehicles use electricity as part of the operation of the vehicle.These vehicles may be operated using electricity exclusively, or byusing a combination of electricity and another energy source. Manymodern vehicles include a power control unit (PCU) configured to managethe energy amongst multiple different vehicle electrical systems. In thecase of vehicles driven by electric motors, a power control unit may beused to control the electric motor, including torque and speed of themotor. A component of the power control unit is a power card, whichcontains power devices that may be switched on and off in high frequencyduring operation of the vehicle. These power devices may generatesignificant amounts of heat. Conventional power cards have designs forexposing surface area of the power devices for cooling purposes.However, these conventional power cards are bulky and not useful incompact space contexts. Thus, there is a need for a power card capableof providing cooling and being compact.

SUMMARY

What is described is a power card for use in a vehicle. The power cardincludes an N lead frame having a body portion and a terminal portion,the terminal portion extending outward from the body portion. The powercard also includes a P lead frame having a body portion and a terminalportion, the terminal portion extending outward from the body portion.The power card also includes an O lead frame having a body portion and acooling portion, the cooling portion extending outward from the bodyportion, the O lead frame being located between the N lead frame and theP lead frame. The power card also includes a first power device beinglocated on a first side of the O lead frame between the body portion ofthe N lead frame and the body portion of the O lead frame. The powercard also includes a second power device being located on a second sideof the O lead frame between the body portion of the O lead frame and thebody portion of the P lead frame, the O lead frame configured to receiveheat from the first power device and the second power device by the bodyportion of the O lead frame and transfer the heat to the cooling portionof the O lead frame for heat dissipation.

Also described is a power system. The power system includes a powercard. The power card includes an O lead frame located between an N leadframe and a P lead frame, the O lead frame having a body portion and acooling portion. The power card also includes a first power devicelocated on a first side of the O lead frame between the N lead frame andthe O lead frame. The power card also includes a second power devicelocated on a second side of the O lead frame between the O lead frameand the P lead frame, the O lead frame configured to receive heat fromthe first power device and the second power device by the body portionof the O lead frame and transfer the heat to the cooling portion of theO lead frame for heat dissipation.

Also described is a lead frame for use in a vehicle power card. The leadframe includes a body portion having a first side coupled to a firstpower device, a second side coupled to a second power device, the bodyportion being configured to absorb heat from the first power device andthe second power device. The lead frame also includes a cooling portionextending outward from the body portion and configured to receive theabsorbed heat from the body portion for heat dissipation.

BRIEF DESCRIPTION OF THE DRAWINGS

Other systems, methods, features, and advantages of the presentinvention will be apparent to one skilled in the art upon examination ofthe following figures and detailed description. Component parts shown inthe drawings are not necessarily to scale, and may be exaggerated tobetter illustrate the important features of the present invention.

FIGS. 1A-IC illustrate a power card, according to various embodiments ofthe invention.

FIGS. 2A-2F illustrate a compact low inductance chip-on-chip power card,according to various embodiments of the invention.

FIGS. 3A-3C illustrate the compact low inductance chip-on-chip powercard connected with a capacitor, according to various embodiments of theinvention.

FIGS. 4A-4D illustrate a method of manufacturing the compact lowinductance chip-on-chip power card, according to various embodiments ofthe invention.

FIGS. 5A-5C illustrate a compact low inductance chip-on-chip power cardwith an O lead frame with integrated channels, according to variousembodiments of the invention.

FIG. 5D illustrates a system using the compact low inductancechip-on-chip power card with an O lead frame with integrated channels,according to various embodiments of the invention.

FIG. 6 illustrates an O lead frame with integrated channels, accordingto various embodiments of the invention.

FIG. 7 illustrates an exploded O lead frame with integrated channels,according to various embodiments of the invention.

FIG. 8 illustrates a compact low inductance chip-on-chip power card witha thermally conductive O lead frame, according to various embodiments ofthe invention.

FIG. 9 illustrates a compact low inductance chip-on-chip power card witha graphite O lead frame, according to various embodiments of theinvention.

FIG. 10 illustrates a graphite O lead frame, according to variousembodiments of the invention.

FIG. 11 illustrates a graphite and copper O lead frame, according tovarious embodiments of the invention.

FIG. 12 illustrates a heat pipe, according to various embodiments of theinvention.

FIG. 13 illustrates a cross-sectional view of a vapor chamber, accordingto various embodiments of the invention.

FIG. 14A-14B illustrate views of a vapor chamber O lead frame, accordingto various embodiments of the invention.

FIG. 15 illustrates an O lead frame with three cooling surfaces,according to various embodiments of the invention.

FIG. 16 illustrates a flowchart of a process of fabricating the system,according to various embodiments of the invention.

DETAILED DESCRIPTION

Disclosed herein are power cards and methods of manufacture thereof. Apower card may be a part of a power control unit of a vehicle. The powercontrol unit is configured to manage the energy amongst multipledifferent vehicle electrical systems. In vehicles with electric motors,the power control unit may be responsible for operation of the electricmotor. The power control unit may include a power card having powerdevices that are switched on and off at high frequencies duringoperations of the vehicle. These power devices may be any switch, suchas an RC-IGBT, an IGBT/diode combination, or a MOSFET, for example.

Conventional silicon-based power cards have an inductance higher than 20nH. If silicon carbide is applied, instead of silicon, to the same powercard structure, being switched at a higher frequency, high switchinglosses will be generated due to the relatively high inductance.

The power card described herein have a lower inductance and a morecompact design. There are many contexts in a vehicle where a morecompact power card may provide many benefits. For example, when avehicle has multiple electric motors driving wheels independently(instead of a central electric motor providing power to the wheels), acompact power card at each wheel may be highly beneficial. A compactpower card may provide for more efficient and lighter weight systems, asthe power card and the motor could share components, such as coolingdevices.

The power card described herein may include O lead frames designed toefficiently cool the power devices of the power card. The O lead framemay include cooling channels for passing a liquid to absorb heat. The Olead frame may include a vapor chamber for cooling heat received fromthe power devices. The O lead frame may also be made of materials havingspecific thermal conductivity characteristics for improved heatabsorption and dissipation.

The power cards described herein may be used with a vehicle. A vehicleis a conveyance capable of transporting a person, an object, or apermanently or temporarily affixed apparatus. The vehicle may have anautomatic or manual transmission. The vehicle may be a self-propelledwheeled conveyance, such as a car, sports utility vehicle, truck, bus,van or other motor or battery driven vehicle. For example, the vehiclemay be an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle,a fuel cell vehicle, or any other type of vehicle that includes amotor/generator.

The vehicle may be capable of non-autonomous operation orsemi-autonomous operation or autonomous operation. That is, the vehiclemay be driven by a human driver or may be capable of self-maneuveringand navigating without human input. A vehicle operatingsemi-autonomously or autonomously may use one or more sensors and/or anavigation unit to drive autonomously.

FIG. 1A illustrates a perspective view of a power card 100 having aside-by-side design. The power card 100 includes two power devices 102located in a co-planar, side-by-side arrangement. The power card 100also includes an O power terminal 104, an N power terminal 106, a Ppower terminal 108, and signal terminals 112. The power card 100 isencased in resin 110, with the power terminals and signal terminalsexposed.

FIG. 1B illustrates a top-down view of the power card 100 having theside-by-side design. As can be seen in FIG. 1B, the power terminals 115(i.e., the O power terminal 104, the N power terminal 106, and the Ppower terminal 108) and the signal terminals 112 are not entirelyencased in resin 110. In addition, the power terminals 115 are locatedon a first end 101 of the power card 100, and the signal terminals 112are located on a second end 103 of the power card 100. The power card100 also includes heat spreaders 114 configured to absorb heat generatedby the power devices 102. Electrical current 116 flows from the P powerterminal 108 to the power devices 102, and through the N power terminal106. The O power terminal serves as an output. For example, when thepower card is used in conjunction with multiple other power cards in aninverter, the P terminal and N terminal of each power card may beconnected to the DC power source, and the O power terminal of each powercard is responsible for outputting one phase of the alternating current,with the combined outputs of the O power terminals creating analternating current. The alternating current may be used to power amotor, for example. When the inverter is bi-directional, alternatingcurrent generated by regenerative braking, for example, could bereceived by the O power terminals of the multiple power cards, and a DCbattery may be recharged using the power cards.

FIG. 1C is a partial side cross-sectional view of the power card 100. Asshown, the power devices 102 are co-planar with each other. One powerdevice 102 is connected to the P power terminal 108 on a first sideusing solder 118, and is connected to a conductive copper spacing block120 on a second side using solder 118. The conductive copper spacingblock 120 is connected to a first heat spreader 114A using solder 118.The first heat spreader 114A has an arm that extends laterally sidewaystoward the N power terminal 106 and is connected (using solder 118) to alaterally-extending arm of a second heat spreader 114B. The second heatspreader 114B is connected to the other power device 102 using solder118. The other power device 102 is connected to the second heat spreader114B on a first side using solder 118, and is connected to a conductivecopper spacing block 120 on a second side using solder 118. Theconductive copper spacing block 120 is connected to the N power terminal106 using solder 118. Electrical current 116 moves upward from the Ppower terminal 108, through a power device 102, down through the heatspreaders 114, through the other power device 102, and through the Npower terminal 106.

FIG. 2A illustrates a power card 200. The power card 200 has achip-on-chip design, where the power devices are located in a verticallystacked arrangement, as compared to the side-by-side design of powercard 100. The chip-on-chip design allows the volume of the power card200 to be reduced by 49% compared to the power card 100 with theside-by-side design.

The power card 200 includes an O lead frame 204 having a terminalportion 222 extending from a body portion 228 (shown in FIGS. 2B and2E). The power card 200 also includes an N lead frame 206 having aterminal portion 226 extending from a body portion 232. The power card200 also includes a P lead frame 208 having a terminal portion 224extending from a body portion 230. The terminal portions are configuredto connect to other vehicle components to connect the power card 200 tothe vehicle. In some embodiments, the body portions of the lead framesmay be referred to as the substrate. Electrical current flows from theterminal portion 224 of the P lead frame 208 to the terminal portion 226of the N lead frame 206. The terminal portion 222 of the O lead frame204 serves as an output. For example, when the power card 200 is used inconjunction with multiple other power cards (similar to power card 200)in an inverter, the terminal portion 224 of the P lead frame 208 and theterminal portion 226 of the N lead frame 206 of each power card may beconnected to the DC power source, and the terminal portion 222 of the Olead frame 204 of each power card is responsible for outputting onephase of the alternating current, with the combined outputs of theterminal portions of the O lead frames of each power card creating analternating current. The alternating current may be used to power amotor, for example. When the inverter is bi-directional, alternatingcurrent generated by regenerative braking, for example, could bereceived by the terminal portions of the O lead frames of the multiplepower cards, and a DC battery may be recharged using the power cards.

The power card 200 has a first end 201 and a second end 203 opposite thefirst end 201. The terminal portion 222 of the O lead frame is locatedat the first end 201 and the terminal portion 226 of the N lead frameand the terminal portion 224 of the P lead frame 208 are located at thesecond end 203. By being on opposite ends of the power card 200, theterminal portions of the O lead frame 204, the N lead frame 206, and theP lead frame 208 may be as wide as the power device. In comparison, thepower terminals 115 of the side-by-side power card 100 are narrower(approximately half the width of the power device 102) because the powerterminals 115 are all on the same end of the power card 100. Inaddition, by having the terminal portion 222 of the O lead frame 204 onthe opposite end as the terminal portion 224 of the P lead frame 208 andthe terminal portion 226 of the N lead frame 206, the terminal portion224 of the P lead frame 208 and the terminal portion 226 of the N leadframe 206 may be located very close to each other and separated by athin insulator. This close location to each other results in very lowinductance for high-speed switching of the power devices.

The power card 200 includes two sets of signal terminals 212, one setfor each of the two power devices. Each set of signal terminals isconnected to a respective power device. The set of signal terminals 212provides connections to the power device, for purposes of providingswitching signals to the power device and also for purposes of detectingdata from the power device. For example, when there are 5 signalterminals in the set of signal terminals 212, one signal terminal mayconnected to the gate of the power device and be used as a gate signalfor switching the power device on and off using low voltage, two signalterminals may be used for detecting temperature, one signal terminal maybe used as a current sensor, and one signal terminal may be used as anemitter voltage sensor.

The power card 200 also includes voltage terminals 250 as being part ofthe P lead frame 208. The voltage terminals 250 may be used to detect avoltage of the power card 200. The voltage terminals 250 extend awayfrom the body portion 230 of the P lead frame 208, but in a directionopposite the terminal portion 224 of the P lead frame 208. Thus, thevoltage terminals 250 are located at the first end 201 of the power card200, alongside the terminal portion 222 of the O lead frame 204. Thevoltage terminals 250 may be located horizontally on either side of theterminal portion 222 of the O lead frame 204.

The power card 200 has a first lengthwise edge 205 and a secondlengthwise edge 207 opposite the first lengthwise edge 205. As shown inFIG. 2A, the sets of signal terminals 212 are located at the firstlengthwise edge 205 and the voltage terminals 250 are located at thefirst end 201. However, in some embodiments, the voltage terminals 250may be removed and the sets of signal terminals 212 may be reduced to asingle signal terminal corresponding to each power device, and thesesingle signal terminals may be located horizontally on either side ofthe terminal portion 222 of the O lead frame 204, similar to thelocation of the voltage terminals 250 in FIG. 2A.

The power card 200 may be partially encased in resin 210. The resin 210may be injection molded to the power card 200 such that all gaps betweenthe components of the power card 200 are occupied with resin 210. Theresin 210 may insulate the components of the power card 200 to allow thepower card 200 to operate more efficiently. The terminal portion 222 ofthe O lead frame 204, the voltage terminals 250, portions of the sets ofsignal terminals 212, a portion of the terminal portion 224 of the Plead frame, and a portion of the terminal portion 226 of the N leadframe may not be covered in resin 210, with the remaining components ofthe power card 200 being encased in resin 210. The exposed portion ofthe terminal portion 224 of the P lead frame may be the top surface ofthe terminal portion 224. The exposed portion of the terminal portion226 of the N lead frame may be the bottom surface of the terminalportion 226.

FIG. 2B illustrates a top-down view of the power card 200, with the bodyportion of the P lead frame 208 made transparent, to show one of the twopower devices 202 and a set of signal terminals 212 connected to thepower device 202. The power device 202 may be any switch, such as anRC-IGBT, an IGBT/diode combination, or a MOSFET, for example.

The body portion 228 of the O lead frame 204 is substantiallysquare-shaped and is located in a central portion of the power card 200,between the first end 201 and the second end 203. Similarly, the bodyportion 230 of the P lead frame 208 is substantially square-shaped andis located in a central portion of the power card 200, between the firstend 201 and the second end 203. In addition, the body portion 232 of theN lead frame 206 is substantially square-shaped and is located in acentral portion of the power card 200, between the first end 201 and thesecond end 203.

Between the body portion 228 of the O lead frame 204 and the powerdevice 202 may be a heat spreader 214. The heat spreader 214 may beformed integrally of the O lead frame 204 at the body portion 228 andmay elevate the power device 202 away from the O lead frame 204. The Nlead frame 206 may have a similar heat spreader, as shown in FIG. 2C.

FIG. 2C illustrates a partial front cross-sectional view of the powercard 200 in a central area of the power card 200 where the body portionsof the lead frames and the power devices are located. The N lead frame206 and the O lead frame 204 have heat spreaders 214 formed integrallyin the respective body portions of the N lead frame 206 and the O leadframe 204. That is, the body portion 232 of the N lead frame 206 has aheat spreader 214 formed integrally in the body portion 232. The heatspreader 214 extends upward and away from the body portion 232 of the Nlead frame 206. The heat spreader 214 extends in a directionperpendicular to the direction that the terminal portion 226 extends in.The heat spreader 214 may have a tapered shape such that the width ofthe heat spreader 214 narrows the further away the heat spreader 214 isfrom the body portion 232 of the N lead frame 206.

The body portion 232 of the N lead frame 206 connects to a first powerdevice 202A (via the heat spreader 214). The body portion 232 of the Nlead frame 206 is connected to the first power device 202A via solder218A. The solder 218A may be applied as a layer between the body portion232 of the N lead frame 206 and the first power device 202A or may beapplied in discrete areas between the body portion 232 of the N leadframe 206 and the first power device 202A.

Similarly, the body portion 228 of the O lead frame 204 has a heatspreader 214 formed integrally in the body portion 228. The heatspreader 214 extends upward and away from the body portion 228 of the Olead frame 204. The heat spreader 214 extends in a directionperpendicular to the direction that the terminal portion 222 extends in.The heat spreader 214 may have a tapered shape such that the width ofthe heat spreader 214 narrows the further away the heat spreader 214 isfrom the body portion 228 of the O lead frame 204.

The heat spreader 214 may be located on a first side of the body portion228 of the O lead frame 204. The first power device 202A may beconnected to the second side of the body portion 228 of the O lead frame204 using solder 218B. The solder 218B may be applied as a layer or indiscrete areas. The second side of the body portion 228 of the O leadframe 204 is opposite the first side of the body portion 228 of the Olead frame 204.

The body portion 228 of the O lead frame 204 connects to a second powerdevice 202B (via the heat spreader 214). The body portion 228 of the Olead frame 204 is connected to the second power device 2028 via solder218C. The solder 218C may be applied as a layer between the body portion228 of the O lead frame 204 and the second power device 202B or may beapplied in discrete areas between the body portion 228 of the O leadframe 204 and the second power device 202B.

The second power device 2028 is connected to the body portion 230 of theP lead frame 208 using solder 218D. Unlike the N lead frame 206 and theO lead frame 204, the P lead frame 208 may not have a heat spreader 214.Again, the heat spreaders 214 serve to provide space for the signalterminals to connect to the signal pads of the power devices 202.Without the heat spreaders 214, there may not be sufficient space forsignal terminals to reach the power devices 202.

As shown in FIG. 2C, electrical current 216 travels from the P leadframe 208 through the two power devices 202 and through the N lead frame206. As compared to electrical current 116 of FIG. 1C of theside-by-side power card 100, the electrical current 216 travels in ashorter, straighter line. This makes the operation of the power card 200more efficient than the power card 100 by reducing self-inductance.

In addition, as compared to the side-by-side power card 100 shown inFIG. 1C, the power card 200 has fewer components, as the side-by-sidepower card 100 includes more components that the power card 200 does notinclude—two conductive copper spacing blocks 120, two layers of solder118 connecting each conductive copper spacing block 120 to anothercomponent, and a layer of solder between the heat spreaders 114. Inaddition, the heat spreaders 114 of the side-by-side power card 100 arebulkier than the integrated heat spreaders 214 of the power card 200.

FIG. 2D illustrates a circuit diagram 252 representing the power card200.

FIG. 2E illustrates a side view of components of the power card 200. Thebody portion 230 of the P lead frame 208 is aligned with the bodyportion 228 of the O lead frame 204 as well as the body portion 232 ofthe N lead frame 206. In addition, the first power device 202A is shownas being between the body portion 232 of the N lead frame 206 and thebody portion 228 of the O lead frame 204. The second power device 202Bis shown as being between the body portion 228 of the O lead frame 204and the body portion 230 of the P lead frame 208.

The terminal portion 224 of the P lead frame 208 is connected to thebody portion 230 of the P lead frame 208 by a bend 234. The body portion230 of the P lead frame lies along a P body plane 238 and the terminalportion 224 of the P lead frame 208 lies along a P terminal plane 244.The P body plane 238 and the P terminal plane 244 are parallel. The bend234 brings the terminal portion 224 of the P lead frame 208 closer tothe N lead frame 206.

The terminal portion 226 of the N lead frame 206 is connected to thebody portion 232 of the N lead frame 206 by a bend 236. The body portion232 of the N lead frame lies along an N body plane 240 and the terminalportion 226 of the N lead frame 206 lies along an N terminal plane 246.The N body plane 240 and the N terminal plane 246 are parallel. The bend236 brings the terminal portion 226 of the N lead frame 206 closer tothe P lead frame 208.

The distance 254 between the body portion 230 of the P lead frame 208and the body portion 232 of the N lead frame 206 is greater than thedistance 256 between the terminal portion 224 of the P lead frame 208and the terminal portion 226 of the N lead frame 206 due to the bends234, 236.

An insulator 220 may be located between the terminal portion 224 of theP lead frame 208 and the terminal portion 226 of the N lead frame 206.The voltage difference between the terminal portion 224 of the P leadframe 208 and the terminal portion 226 of the N lead frame 206 isrelatively high. The insulator 220 may be configured to assist inreducing inductance between the P terminal and the N terminal. Theinsulator 220 may span the entire length of the terminal portion 224 ofthe P lead frame 208 and the terminal portion 226 of the N lead frame206, or may occupy a portion thereof. The insulator 220 may be made ofceramic or any other insulating material. The insulator 220 may be verythin—approximately 320 μm thick. The insulator 220 may occupy the entiredistance 256 between the terminal portion 224 of the P lead frame 208and the terminal portion 226 of the N lead frame 206.

The body portion 228 of the O lead frame 204 has a top surface that liesalong an O plane 242. The terminal portion 222 of the O lead frame 204may also lie along the O plane 242 such that a top surface of the bodyportion 228 of the O lead frame is coplanar to a top surface of theterminal portion 222 of the O lead frame 204.

The voltage terminals 250 of the P lead frame 208 may extend in adirection opposite the terminal portion 224 of the P lead frame 208. Thevoltage terminals 250 may be connected to the body portion 230 of the Plead frame 208 by a bend, and the voltage terminals 250 may lie alongthe O plane 242.

FIG. 2F illustrates an embodiment of the power card 200 without voltageterminals 250 of the P lead frame 208. The view of FIG. 2F is a top-downview of the power card 200, with the body portion of the P lead frame208 made transparent, to show the second power device 202B, similar toFIG. 2B. The first power device 202A is obscured by the O lead frame204.

In embodiments where the voltage terminals 250 are not present, the setsof signal terminals 212 may be replaced by a single signal terminal 260Afor the first power device 202A and a single signal terminal 2608 forthe second power device 202B. Both of the single signal terminals 260may lie along the O plane 242, similar to the previously-present voltageterminals 250.

The signal terminals 260 may receive signals for switching on and offtheir respective devices. That is, the first signal terminal 260A mayreceive signals for switching on and off the first power device 202A andthe second signal terminal 260B may receive signals for switching on andoff the second power device 202B.

The power devices 202 may be rotated to allow the contacts of the powerdevices 202 to be close to the signal terminals 260 and allowing thesignal terminals 260 to be as short as possible. While FIG. 2Fillustrates the signal terminals 260 as being on either side of theterminal portion 222 of the O lead frame 204, the signal terminals 260may be located at any other location on the power card (e.g., along thelengthwise edges). Also, while FIG. 2F illustrates the signal terminals260 as extending outward with a length that is a fraction of the lengthof the terminal portion 222 of the O lead frame 204, the signalterminals 260 may be of any length.

FIG. 3A illustrates a system 300 using the power card 200. The terminalportion 224 of the P lead frame 208 and the terminal portion 226 of theN lead frame 206 are connected to a capacitor 308 via a P bus bar 304and an N bus bar 306, respectively. That is, the P bus bar 304 isconnects a second end 340 of the capacitor 308 to the terminal portion224 of the P lead frame 208. In particular, a bottom surface of the Pbus bar 304 contacts a top surface of the terminal portion 224 of the Plead frame 208. In addition, the N bus bar 306 connects a first end 342of the capacitor 308 to the terminal portion 226 of the N lead frame206. In particular, a top surface of the N bus bar 306 contacts a bottomsurface of the terminal portion 226 of the N lead frame 206.

The N bus bar 306 has a first portion 330 and a second portion 328. Thefirst portion 330 connects to the terminal portion 226 of the N leadframe 206. In particular, a top surface of the first portion 330 of theN bus bar 306 contacts a bottom surface of the terminal portion 226 ofthe N lead frame 206. The second portion 328 contacts the first end 342of the capacitor 308. The first portion 330 and the second portion 328both lie along a first plane 336. The first plane 336 is parallel to theN terminal plane 246.

The P bus bar 304 has a first portion 322, a second portion 324, and athird portion 326. The first portion 322 connects to the terminalportion 224 of the P lead frame 208. In particular, the bottom surfaceof the first portion 322 connects to the top surface of the terminalportion 224 of the P lead frame 208. The first portion 322 lies along asecond plane 334 that is parallel to the P terminal plane 244. Thesecond plane 334 is also parallel to the first plane 336.

The second portion 324 of the P bus bar 304 travels up a side of thecapacitor 308. The second portion 324 lies along a third plane 338perpendicular to the first plane 336 and the second plane 334.

The third portion 326 of the P bus bar 304 connects to a second end 340of the capacitor 308. The third portion 326 lies along a fourth plane332 that is parallel to the first plane 336 and the second plane 334 andperpendicular to the third plane 338.

As shown by the arrows, an electrical current flows through the P leadframe 208 (314A), through the first portion 322 of the P bus bar 304(316A), through the third portion 326 of the P bus bar 304 (320A),through the second portion 328 of the N bus bar 306 (320B), through thefirst portion 330 of the N bus bar 306 (316B), and through the N leadframe 206 (314B).

Each current flow has a complementary opposite current flow to reduceparasitic inductance. The current flow 314A is complemented by currentflow 314B, current flow 316A is complemented by current flow 316B,current flow 318A is complemented by current flow 318B, and current flow320A is complemented by current flow 320B.

FIG. 3B is a magnified view of the power card 200. A first heat sink302A is connected to the body portion 230 of the P lead frame 208 and asecond heat sink 302B is connected to the body portion 232 of the N leadframe 206. The heat sinks 302 are configured to cool the respective leadframes.

FIG. 3C is a perspective view of the system 300. The power card 200 hasa width 312, and the P bus bar 304, the N bus bar 306, and the capacitor308 have a width 310. The width 310 may be as wide as the application ofthe system 300 will allow, in order to reduce current density throughthe P bus bar 304, the N bus bar 306, and the capacitor 308. Theterminal portions of the N lead frame 206, the P lead frame 208, and theO lead frame 204 may also be as wide as possible to reduce currentdensity. As compared to the N power terminal 106, the P power terminal108, and the O power terminal 104, the terminal portions of the N leadframe 206, the P lead frame 208, and the O lead frame 204 are at leasttwice as wide. The N power terminal 106, the P power terminal 108, andthe O power terminal 104 may be half the width of the power device, andthe terminal portions of the N lead frame 206, the P lead frame 208, andthe O lead frame 204 may be as wide as the power device.

Simulations of the systems described herein using power card 200demonstrate a significant decrease in inductance compared to the powercard 100. The inductance from the power card 200 is 1.90 nH, compared to19.3 nH of the power card 100. Thus, the power card 200 reducesinductance by 90% and volume by 49% compared to power card 100.

FIGS. 4A-4D illustrate a process of manufacturing the power card 200.FIG. 4A shows a power device 202 having signal pads 402. The signal pads402 are configured to connect to signal terminals of a set of signalterminals (e.g., set of signal terminals 212). Solder 403 is applied tothe signal pads 402.

FIG. 4B illustrates solder being applied to the O lead frame 204 and theN lead frame 206. The O lead frame 204 and the N lead frame 206 areplaced in a lower moat 408 and an upper moat 406 is removably placed ontop of the O lead frame 204 and the N lead frame 206. In particular, theO lead frame 204 is placed in and received by a cavity 416 formed in thelower moat 408, and the N lead frame 206 is placed in and received by acavity 414 formed in the lower moat 408. A first side (or “top side” or“upper side”) 458 of the O lead frame 204 contacts the upper moat 406and a second side (or “bottom side” or “lower side”) 460 of the O leadframe 204 contacts the lower moat 408. Similarly, a first side (or “topside” or “upper side”) 452 of the N lead frame 206 contacts the uppermoat 406 and a second side (or “bottom side” or “lower side”) 454 of theN lead frame 206 contacts the lower moat 408.

The O lead frame 204 has an elevated heat spreader 214 formed integrallyin the body portion 228 of the O lead frame 204. Similarly, the N leadframe 206 has an elevated heat spreader 214 formed integrally in thebody portion 232 of the N lead frame 206. The elevated heat spreader 214of the O lead frame 204 has a surface 456 and the elevated heat spreader214 of the N lead frame 206 also has a surface 450.

When the O lead frame 204 and the N lead frame 206 are located betweenthe upper moat 406 and the lower moat 408, the surface 456 of the O leadframe 204 and the surface 450 of the N lead frame 206 are exposed via anO lead frame opening 410 and an N lead frame opening 412, respectively,of the upper moat 406. When the surface 456 of the O lead frame 204 andthe surface 450 of the N lead frame 206 are exposed, solder 418 may beapplied to the surface 456 of the O lead frame 204 and the surface 450of the N lead frame 206.

Similarly, when the O lead frame 204 and the N lead frame 206 arelocated between the upper moat 406 and the lower moat 408, portions ofthe body portions of the O lead frame 204 and the N lead frame 206 maybe exposed via openings 428 of the upper moat 406. Solder 404 may beapplied to the exposed portions of the body portions of the O lead frame204 and the N lead frame 206 via the openings 428 of the upper moat 406.

The upper moat 406, lower moat 408, the O lead frame 204, the N leadframe 206, and the solder 404, 418 are heated so that the solder 404,418 attaches to its respective contacting surfaces on the O lead frame204 and the N lead frame 206. The solder 418 will be used to couple therespective lead frame to a respective power device 202, and the solder404 will be used to secure a respective set of signal terminals 212 tothe respective lead frame.

Once the solder has cooled and set, the upper moat 406 is removed, andthe O lead frame 204 and the N lead frame 206 are removed from the lowermoat 408.

FIG. 4C illustrates power devices 202 being connected to the O leadframe 204 and the N lead frame 206. As compared to FIG. 4B, the O leadframe 204 and the N lead frame 206 are turned upside down, such that thefirst side 458 of the O lead frame 204 faces downward and the secondside 460 of the O lead frame 204 faces upward, and the first side 452 ofthe N lead frame 206 faces downward and the second side 454 of the Nlead frame 206 faces upward.

A moat 420 has a first cavity 422 for receiving solder 426 and a secondcavity 424 also for receiving solder 426. A first power device 202A isplaced on top of the solder 426 in the first cavity 422. Morespecifically, a second side 482 of the first power device 202A contactsthe solder 426.

The N lead frame 206 is placed on top of the first side 480 of the firstpower device 202A. The solder 418 on the first side 452 of the N leadframe 206 contacts the first side 480 of the first power device 202A andcouples the first power device 202A to the N lead frame 206.

Sandwiched between the first power device 202A and the N lead frame 206is a set of signal terminals 212. The set of signal terminals 212 has aplurality of signal terminals 466 and a set of testing terminals 464used to test the power card. The signal terminals 466 of the set ofsignal terminals 212 are connected to the signal pads 402 of the firstpower device 202A using solder 403. The testing terminals 464 areconnected to the body portion 232 of the N lead frame 206 via solder404. In some embodiments, there are no testing terminals 464, and onlysignal terminals 466. In some embodiments, there is only one signalterminal instead of the set of signal terminals, where the single signalterminal is a gate signal used for switching the first power device 202Aon and off.

A second power device 202B is placed on top of the solder 426 in thesecond cavity 424. More specifically, a second side 482 of the secondpower device 202B contacts the solder 426.

The O lead frame 204 is placed on top of the first side 480 of thesecond power device 202B. The solder 418 on the first side 458 of the Olead frame 204 contacts the first side 480 of the second power device202B and couples the second power device 202B to the O lead frame 204.

Sandwiched between the second power device 202B and the O lead frame 204is a set of signal terminals 212. The set of signal terminals 212 has aplurality of signal terminals 466 and a set of testing terminals 464used to test the power card. The signal terminals 466 of the set ofsignal terminals 212 are connected to the signal pads 402 of the secondpower device 202B using solder 403. The testing terminals 464 areconnected to the body portion 228 of the O lead frame 204 via solder404. In some embodiments, them are no testing terminals 464, and onlysignal terminals 466. In some embodiments, there is only one signalterminal instead of the set of signal terminals, where the single signalterminal is a gate signal used for switching the second power device202B on and off.

All of the components are heated so that the solder can attach to itsrespective contacting surfaces. The N lead frame 206 having the firstpower device 202A attached to it and the O lead frame 204 having thesecond power device 202B attached to it are removed from the moat 420once the solder has cooled and set.

FIG. 4D illustrates the P lead frame 208, the O lead frame 204, and theN lead frame 206 being combined into the power card 200. The moat 468has a cavity 470 configured to receive the N lead frame 206. Inparticular, the second side 454 of the N lead frame 206 contacts thecavity 470 of the moat 468. The first side 452 of the N lead frame 206faces the second side 460 of the O lead frame 204. The second side 482of the first power device 202A faces the second side 460 of the O leadframe 204 and connects to the body portion 228 of the O lead frame 204via solder 426.

The first side 458 of the O lead frame 204 faces the second side 474 ofthe P lead frame 208. The second side 482 of the second power device202B faces the second side 474 of the P lead frame 208 and connects tothe body portion 230 of the P lead frame 208 via solder 426. The firstside 472 of the P lead frame 208 faces upward.

All of the components are heated so that the solder can attach to itsrespective contacting surfaces. A spacer 476 may temporarily be disposedbetween the two sets of signal terminals 212 to provide support for thesets of signal terminals 212 while the solder connecting the sets ofsignal terminals 212 to the lead frame and power device cools and sets.An insulator 220 may be disposed between the terminal portion 224 of theP lead frame 208 and the terminal portion 226 of the N lead frame 206.

Once the solder has set, the spacer 476 is removed, and the intermediateassembly including the P lead frame 208, the O lead frame 204, the Nlead frame 206, the first power device 202A, the second power device202B, the sets of signal terminals 212, and the solder disposedtherebetween, may be placed in a mold. The resin 210 may be injectedinto the mold such that the resin 210 fills all gaps between componentsof the intermediate assembly. Once the resin 210 is cured, additionalfinishing steps (e.g., cutting the resin to expose metal parts on thetop and bottom of the power card, signal terminal cutting, cleaning) maybe performed, and the power card 200 fabrication is complete.

As described herein, the resin 210 may not cover all of the componentsof the power card 200. In particular, the resin 210 may not cover theterminal portion 222 of the O lead frame 204, the top surface of theterminal portion 224 of the P lead frame 208 (e.g., the terminal portion224 of the first side 472 of the P lead frame 208), and the bottomsurface of the terminal portion 226 of the N lead frame 206 (e.g., theterminal portion 226 of the second side 454 of the N lead frame 206).

Any of the moats (e.g., upper moat 406, lower moat 408, moat 420, moat468) may be made of graphite or other similar durable materials. Themoats may also have any number of support features for supporting andframing the components received in the moat cavity, as shown in FIGS.48-4D.

Because of the stacked arrangement of the power devices 202, the powercard 200 may generate significant amounts of heat. In some embodiments,cooling may be provided on both sides of each power device 202 toimprove the cooling of the power card 200. When the power card 200 isnot sufficiently cooled, thermal resistivity may rise, and the powercard 200 may not operate as efficiently.

FIG. 5A illustrates a side view of a power card 500 having an O leadframe 504 with integrated cooling. The power card 500 is similar topower card 200 described herein. Components of power card 200 that aredifferent in power card 500 may be numbered with different referencenumbers than those used with respect to power card 200.

Power card 500 includes P lead frame 208, N lead frame 206, a firstpower device 202A, a second power device 202B, a single signal terminal260A for the first power device 202A, a single signal terminal 260B forthe second power device 202B, a first heat sink 302A, and a second heatsink 302B, each as described herein. These components, along with the Olead frame 504 are encased in resin 210, as described herein.

The O lead frame 504 has a body portion 506 and a terminal portion 508extending outward from the body portion 506. The first power device 202Ais coupled to a first side 554 of the O lead frame 504 (specifically,the body portion 506 of the O lead frame) and the second power device202B is coupled to a second side 556 of the O lead frame 504(specifically, the body portion 506 of the O lead frame).

The body portion 506 of the O lead frame 504 includes an O channel 502,which may be one or more channels. The O channel 502 is configured toreceive cooling liquid and allow the cooling liquid to pass through theO channel 502. When the cooling liquid is within the O channel 502, thecooling liquid absorbs heat emitted from the first power device 202A andthe second power device 202B. The now-heated cooling liquid exits the Ochannel 502 to be cooled, and as the now-heated cooling liquid exits theO channel 502, new, cooler cooling liquid takes its place in the Ochannel 502 for absorbing heat. The cooling liquid may be any liquidcapable of being heated and cooled efficiently, such as dielectriccoolant or oil.

The combination of the heat sinks 302 and the O lead frame 504 withchannels 502 provides cooling to both sides of each power device 202.That is, the first power card 202A is cooled on a first side by thesecond heat sink 302B and on a second side by the O lead frame 504, andthe second power card 202B is cooled on a first side by the O lead frame504 and on a second side by the first heat sink 302A.

FIG. 58 illustrates the power card 500 with a manifold 512 locatedaround a central portion of the power card 500. The central portion ofthe power card 500 may be delineated by the body portions of the P leadframe 208, the N lead frame 206, and the O lead frame 504 along acenterline axis 538 of the power card 500.

The manifold 512 may surround and encase a central portion of the powercard 500, wrapping around the central portion of the power card 500, toform multiple fluidly coupled channels, including the O channel 502. Themultiple channels may include a top channel 514 and a bottom channel516. The top channel 514 may be located radially outward of the bodyportion 230 of the P lead frame 208, relative to the centerline axis538. The bottom channel 516 may be located radially outward of the bodyportion 232 of the N lead frame 206, relative to the centerline axis538. The top channel 514 and the bottom channel 516 may each be definedby an interior surface of the manifold 512 and an exterior of the powercard 500.

Further, the top channel 514 may be a plurality of channels defined bythe tins 552 of the first heat sink 302A, and the bottom channel 516 maybe a plurality of channels defined by the fins 552 of the second heatsink 302B. That is, the top channel 514 may be a plurality of channelshaving a bottom and side surface defined by the fins 552 of the firstheat sink 302A and a top surface defined by an interior surface of themanifold 512, and the bottom channel 516 may be a plurality of channelshaving a top and side surface defined by the fins 552 of the second heatsink 302B and a bottom surface defined by an interior surface of themanifold 512. The top channel 514 and the bottom channel 516 may lie onplanes that are parallel to the planes that the lead frames lie on.

The top channel 514 is configured to receive cooling liquid and allowthe cooling liquid to pass through the top channel 514. When the coolingliquid is within the top channel 514, the cooling liquid absorbs heatemitted from the second power device 202B and the first heat sink 302A.The now-heated cooling liquid exits the top channel 514 to be cooled,and as the now-heated cooling liquid exits the top channel 514, new,cooler cooling liquid takes its place in the top channel 514 forabsorbing heat.

The bottom channel 516 is configured to receive cooling liquid and allowthe cooling liquid to pass through the bottom channel 516. When thecooling liquid is within the bottom channel 516, the cooling liquidabsorbs heat emitted from the first power device 202A and the secondheat sink 302B. The now-heated cooling liquid exits the bottom channel516 to be cooled, and as the now-heated cooling liquid exits the bottomchannel 516, new, cooler cooling liquid takes its place in the bottomchannel 516 for absorbing heat.

The manifold 512 also includes an inlet port 510 for receiving thecooling liquid for passing through the O channel 502, the top channel514, and the bottom channel 516. A vertically oriented inlet sidechannel 520 may fluidly connect the inlet port to the top channel 514and the bottom channel 516, allowing the cooling liquid to flow 518 tothe top channel 514 and the bottom channel 516 when received via theinlet port 510. The resin 210 encasing the power card 500 prevents thecooling liquid from contacting components of the power card 500 otherthan the O channel 502, the top channel 514, and the bottom channel 516.In particular, the cooling liquid does not contact the power devices 202or the P lead frame 208 or the N lead frame 206.

The manifold 512 also includes an outlet port on an opposite side of theinlet port 510 for expelling the used cooling liquid from the O channel502, the top channel 514, and the bottom channel 516. A verticallyoriented outlet side channel may fluidly connect the outlet port to thetop channel 514 and the bottom channel 516.

The top channel 514, bottom channel 516, inlet side channel 520, andoutlet side channel may span substantially the entire length of themanifold 512 or may span a portion of the manifold 512. The O channel502, the top channel 514, and the bottom channel 516 may spansubstantially the entire width of the manifold 512. The top channel 514,bottom channel 516, inlet side channel 520, and outlet side channel mayinclude multiple channels or may be single respective channels.

The manifold 512 may also include a front face 540 and a rear face 542that are parallel to each other and perpendicular to the respectiveplanes that the top channel 514, bottom channel 516, inlet side channel520, and outlet side channel lie on.

Since the cooling is direct liquid cooling, heat from the power devices202 will be absorbed by the cooling liquid and the heat will not passthrough the manifold 512. Thus, the manifold 512 may be made of anon-thermally/electrically conductive material, such as PEEK or plastic.The insulated manifold material and use of a dielectric coolant reducethe possibility for a short circuit.

FIG. 5C illustrates a perspective view of the power card 500 shown inFIG. 5B. In particular, FIG. 5C shows the outlet port 528 and the outletside channel 522. The manifold 512 spans a lengthwise periphery 558 ofthe body portion 232 of the N lead frame 206, the body portion 230 ofthe P lead frame 208, and the body portion 506 of the O lead frame 504.

The inlet port 510 is coupled to an inlet tube 524. The inlet tube 524connects to a cooling device that provides the cooling liquid to flow518 through the channels of the manifold and the channels of the O leadframe 504. The outlet port 528 is coupled an outlet tube 526. The outlettube 526 connects to the cooling device that receives the used coolingliquid that flowed through the channels of the manifold and the channelsof the O lead frame 504 and absorbed heat from the first power device202A and the second power device 202B. The cooling device cools the usedcooling liquid and provides the cooled cooling liquid to the manifold512 via the inlet tube 524.

While the inlet port 510 and the inlet tube 524 are shown as being onthe first lengthwise edge 534 and the outlet port 528 and the outlettube 526 are shown as being on the second lengthwise edge 536, in otherembodiments, the inlet port 510 and the inlet tube 524 may be on thesecond lengthwise edge 536 and the outlet port 528 and the outlet tube526 may be on the first lengthwise edge 534. In other embodiments, theinlet port 510 and the inlet tube 524 may be on another surface of themanifold 512 and the outlet port 528 and the outlet tube 526 may be onyet another surface of the manifold 512.

As the inlet port 510, inlet tube 524, outlet port 528, and outlet tube526 occupy the lengthwise edges of the power card 500, (e.g., signalterminals 212 of FIGS. 2A-2B) may not be located on either lengthwiseedge, and single signal terminals 260 for each of the power devices 202are located on either side of the terminal portion of the O lead frame.

FIG. 5D is a block diagram of a system 550 using the power card 500. Thepower card 500 is connected to the manifold 512, as described herein.The manifold 512 is connected to a liquid cooler 530, which providescooled cooling liquid to the manifold 512 and receives used coolingliquid from the manifold 512. The liquid cooler 530 cools the usedcooling liquid and provides the cooled liquid to the manifold 512. Theliquid cooler 530 may cool the used cooling liquid using a radiator, forexample.

The liquid cooler 530 is also connected to a vehicle device 532 andcirculates cooling liquid to the vehicle device 532 to cool componentsof the vehicle device 532. The vehicle device 532 may be any vehiclecomponent that generates heat, such as an electronic control unit, amotor, a brake, or an engine, for example. By using a single liquidcooler 530 across multiple devices (e.g., power card 500 and vehicledevice 532), the vehicle is able to reduce complexity, cost, weight, andmaintenance demand, among other things.

When the vehicle device 532 is a motor powering a wheel of a vehicle,the system 550 may be sufficiently compact to be located proximal to thewheel of the vehicle. The vehicle may include additional similar systems550 for each wheel.

FIG. 6 illustrates an O lead frame 604 similar to O lead frame 504. TheO lead frame 604 includes a plurality of channels 602 (similar to Ochannel 502) for receiving cooling liquid. The channels 602 may beformed in the body portion 606 (similar to body portion 506) of the Olead frame 604. The O lead frame 604 may also include a terminal portion608 (similar to terminal portion 508) extending from the body portion606.

The channels 602 may span a width of the O lead frame 604. The channels602 may each have the same cross-sectional area, or the channels 602 mayhave varying cross-sectional areas. The channels 602 may be straightlines through the width of the O lead frame 604 or may be curved pathstraversing the body portion 606 of the O lead frame 604.

The channels 602 may be formed integrally in the body portion 606 of theO lead frame 604. The channels 602 may be etched or machined out of asolid O lead frame 604. The channels 602 may be cast using a mold thatincludes the channels 602. In other embodiments, the O lead frame may beconstructed using multiple pieces.

FIG. 7 illustrates an O lead frame 704 similar to O lead frame 504. TheO lead frame 704 includes a plurality of channels 702 (similar to Ochannel 502) for receiving cooling liquid. The channels 702 may beformed in the body portion 706 (similar to body portion 506) of the Olead frame 704. The O lead frame 704 may also include a terminal portion708 (similar to terminal portion 508) extending from the body portion706.

The channels 702 may span a width of the O lead frame 704. The channels702 may each have the same cross-sectional area, or the channels 702 mayhave varying cross-sectional areas. The channels 702 may be straightlines through the width of the O lead frame 704 or may be curved pathstraversing the body portion 706 of the O lead frame 704.

The O lead frame 704 may be made of two components—a top portion 714 anda bottom portion 712. The top portion 714 includes the terminal portion708 and the channels 702 formed integrally within the top portion 714.The bottom portion 712 is substantially flat and forms the base of the Olead frame 704. The bottom portion 712 may be attached to the topportion 714 along a front edge 716 and a rear edge 718 using solder 710.

When the O lead frame is a single piece, such as O lead frame 604,manufacture of a power card 500 is similar to the manufacture of powercard 200, as described in FIGS. 4A-4D. The primary changes would bemanufacture of the O lead frame 504 described herein and a modified moldfor the resin 210.

When the O lead frame is made of multiple pieces, such as O lead frame704, manufacture of a power card 500 may be made simpler than theprocess described in FIGS. 4A-4D. The top portion 714 may be substitutedfor the O lead frame 204 as shown in FIGS. 4B and 4C and describedherein. Then, instead of performing a solder reflow process of theentire power card, as shown in FIG. 41), a first sub-card and secondsub-card are fabricated.

The first sub-card has the P lead frame 208, the second power device202B, a single signal terminal 260, the top portion 714 of the O leadframe 704, and solder located between the P lead frame 208 and thesecond power device 202B, solder located between the second power device202B and the top portion 714 of the O lead frame 704, and solderconnecting a contact pad of the second power device 202B to the singlesignal terminal 260. The components of the first sub-card may besoldered together using a moat and heating the first sub-card in themoat, to create reflow soldering.

The second sub-card has the N lead frame 206, the first power device202A, a single signal terminal 260, the bottom portion 712 of the O leadframe 704, and solder located between the N lead frame 206 and the firstpower device 202A, solder located between the first power device 202Aand the bottom portion 712 of the O lead frame 704, and solderconnecting a contact pad of the first power device 202A to the singlesignal terminal 260. The components of the second sub-card may besoldered together using a moat and heating the second sub-card in themoat, to create reflow soldering.

The first sub-card and the second sub-card may then be connected usingsolder 710, as shown in FIG. 7 to complete fabrication of the powercard.

In addition to or in lieu of the O lead frame 504 with the O channel502, the O lead frame may be made of a material with thermalconductivity properties that allow for more efficient cooling of the Olead frame, and therefore mom efficient cooling of the power devices202.

FIG. 8 illustrates a power card 800 that has a thermally conductive Olead frame 804. The O lead frame 804 has a body portion 806 and acooling portion 808 extending from the body portion 806 toward a firstend 820 of the power card 800. The cooling portion 808 is connected tothe body portion 806 and cools the body portion 806. The power card 800is similar to power card 200 described herein. Components of power card200 that are different in power card 800 may be numbered with differentreference numbers than those used with respect to power card 200.

Power card 800 includes a P lead frame 208 (with a body portion 230), anN lead frame 206 (with a body portion 232), a first power device 202A, asecond power device 202B, and resin 210 encasing the components of thepower card 800, as described herein. The N lead frame 206 and the P leadframe 208 have respective terminal portions extending from theirrespective body portions and toward a second end 818 of the power card800.

The first power device 202A and the second power device 202B generateheat 810 as they operate. In particular, the heat generated from thefirst power device 202A passes through the body portion 230 of the Plead frame 208, and the heat generated from the second power device 202Bpasses through the body portion 232 of the N lead frame 206. The heatfrom both the first power device 202A and the second power device 202Bmay be encountered by the body portion 806 of the O lead frame 804. Theheat encountered by the O lead frame 804 may be absorbed by the bodyportion 806 and cooled using the cooling portion 808.

The O lead frame 804 may be made of a highly thermally conductivematerial, so that the heat is efficiently conducted from the bodyportion 806 to the cooling portion 808. The cooling portion 808 may havea relatively large surface area for releasing the conducted heat. Inparticular, the cooling portion 808 may have a top surface 822 and abottom surface 824 located radially outward of the top and bottomsurfaces of the body portion 806 of the O lead frame 804, and alsomultiple side surfaces 826 extending between the top surface 822 and thebottom surface 824 of the cooling portion 808 of the O lead frame 804.The multiple side surfaces 826 are perpendicular to the top surface 822and the bottom surface 824. The side surfaces 826, the top surface 822,and the bottom surface 824 create a relatively large surface area forcooling heat 810 received by the body portion 806 of the O lead frame804.

The top surface 822 may be coplanar with a radially outermost surface832 of the P lead frame 208 (e.g., the first side 472 of the P leadframe 208). The bottom surface 824 may be coplanar with a radiallyoutermost surface 834 of the N lead frame 206 (e.g., second side 454 ofthe N lead frame 206). As such, the cooling portion 808 of the O leadframe 804 may be non-overlapping with the body portions of the P leadframe 208 and the N lead frame 206.

In some embodiments, the cooling portion 808 is also attached toseparate cooling devices, such as heat sinks or liquid cooling devicesto further improve cooling.

FIG. 9 illustrates an O lead frame 804 made of graphite. The thermalconductivity of graphite is not homogeneous. Graphite has high thermalconductivity in two axes, but low thermal conductivity along a thirdaxis. The thermal conductivity properties of the O lead frame 804 isshown on the 3-dimensional axes as k_(xx), k_(yy), and k_(zz). Thethermal conductivity along the lengthwise axis of the O lead frame(e.g., axis 538) is represented by k_(xx). The thermal conductivityalong the widthwise axis of the O lead frame 804 is represented byk_(yy). The thermal conductivity along the vertical axis of the O leadframe 804 is represented by k_(zz). The O lead frame 804 may be made sothat the two axes of the graphite with high thermal conductivity arek_(xx) and k_(zz) and the axis with low thermal conductivity is k_(yy).

As shown in FIG. 10, heat 812A received by the body portion 806 of the Olead frame 804 from the first power device 202A and the heat 812Breceived by the body portion 806 of the O lead frame 804 from the secondpower device 202B are easily absorbed by the O lead frame 804 (along thek_(zz) axis). The heat 814 is efficiently directed toward the coolingportion 808 (along the k_(xx) axis) which is cooler than the bodyportion 806. The heat 816A is then directed (along the k_(zz) axis) tothe bottom surface 824 (or attached cooling device) and the heat 816B isdirected (along the k_(zz) axis) to the top surface 822 (or attachedcooling device). The heat 814 may also continue to the side surfaces 826(along the k_(xx) axis).

A thickness 828 of the cooling portion 808 may be greater than athickness 830 of the body portion 806. The increased thickness and thegreater surface area described herein contribute to the coolingcapabilities of the cooling portion 808.

FIG. 11 illustrates an O lead frame 1104 made of a combination of twomaterials. The O lead frame 1104 has a body portion 1106, a coolingportion 1108, a power device platform 1102, and a transition portion1110. The body portion 1106 and the cooling portion 1108 are similar tobody portion 806 and cooling portion 808 described herein.

The platform 1102 is configured to contact power devices 202 on eitherside of the platform 1102. That is, the platform 1102 has a first side1112A configured to contact a first power device 202A and a second side1112B opposite the first side 1112A and configured to contact a secondpower device 202B. FIG. 11 shows the second side 1112B of the platform1102 and the elevation of the platform 1102 from the rest of the bodyportion 1106. Similarly, the platform 1102 is elevated from the rest ofthe body portion 1106 on the first side 1112A.

The transition portion 1110 may be optional and connects the platform1102 to the body portion 1106. In some embodiments, the transitionportion 1110 spans the thickness of the body portion 1106, such that thetransition portion 1110 occupies an aperture in the body portion 1106.In other embodiments, the transition portion 1110 is located on top ofthe body portion 1106 on the top and bottom surfaces of the body portion1106. In other embodiments, the transition portion 1110 spans a portionof the thickness of the body portion 1106, such that the transitionportion 1110 occupies a cavity in the body portion 1106 on the top andbottom surfaces of the body portion 1106.

When the platform 1102 and the transition portion 1110 are made of thesame material, the platform 1102 may be formed integrally with thetransition portion 1110. When the platform 1102 and the transitionportion 1110 are made of different materials, the platform 1102 may belocated on top of the transition portion 1110 on the top and bottomsurfaces of the transition portion 1110, or platform 1102 may occupy acavity in the transition portion 1110 on the top and bottom surfaces ofthe transition portion 1110.

The body portion 1106 and the cooling portion 1108 may be made of afirst material (e.g., graphite) and the platform 1102 and transitionportion 1110 may be made of a second material (e.g., copper). The firstmaterial may have a greater thermal conductivity than the secondmaterial. As a result, if the power devices 202 were to generate heatunevenly (e.g., “local hot spots”), the uneven heat would be spreadacross the platform 1102 and the transition portion 1110 before reachingthe body portion 1106. The uneven heat is spread across the platform1102 and the transition portion 1110 more than if the platform 1102 werealso made of the first material. Once the heat reaches the body portion1106 made of the first material, the heat would be conducted as shown inFIG. 10 and described herein.

The body portion 1106, the cooling portion 1108, and the transitionportion 1110 may be made of a first material (e.g., graphite) and theplatform 1102 may be made of a second material (e.g., copper). The firstmaterial may have a greater thermal conductivity than the secondmaterial. As a result, if the power devices 202 were to generate heatunevenly (e.g., “local hot spots”), the uneven heat would be spreadacross the platform 1102 before reaching the transition portion 1110 andthe body portion 1106. The uneven heat is spread across the platform1102 more than if the platform 1102 were also made of the firstmaterial. Once the heat reaches the body portion 1106 made of the firstmaterial, the heat would be conducted as shown in FIG. 10 and describedherein.

The body portion 1106 and the cooling portion 1108 may be made of afirst material (e.g., graphite), the platform 1102 may be made of asecond material (e.g., copper), and the transition portion 1110 may bemade of a third material. The first material may have a greater thermalconductivity than the second material and the third material. As aresult, if the power devices 202 were to generate heat unevenly (e.g.,“local hot spots”), the uneven heat would be spread across the platform1102 and the transition portion 1110 before reaching the body portion1106. The uneven heat is spread across the platform 1102 and thetransition portion 1110 more than if the platform 1102 or the transitionportion 1110 were also made of the first material. Once the heat reachesthe body portion 1106 made of the first material, the heat would beconducted as shown in FIG. 10 and described herein.

In some embodiments, the third material has a greater thermalconductivity than the second material, to transition the heat flow fromthe second material to the first material. In other embodiments, thethird material has a lower thermal conductivity than the second materialto further spread out the heat across the transition portion 1110.

In some embodiments, the O lead frame 1104 is similar to O lead frame804 and made of the first material, but is coated with the secondmaterial. Thus, instead of the platform 1102 being made of the secondmaterial, the entire surface of the O lead frame 1104 is coated with thesecond material. In these embodiments, the mechanical rigidity of the Olead frame 1104 may increase.

In some embodiments, the platform 1102 is divided into two pieces, witha first piece coupled to a first side of the body portion 1106 of the Olead frame 1104 and also coupled to a first power device, and a secondpiece coupled to a second side of the body portion 1106 of the O leadframe 1104 and also coupled to a second power device.

In other embodiments, the platform 1102 is a single piece having a firstside 1112A and a second side 1112B, and the platform 1102 spans thethickness of the body portion 1106 and is located within an aperture ofthe body portion 1106 of the O lead frame 1104.

In some embodiments, the O lead frame has an integrated vapor chamber orheat pipe to improve cooling. FIG. 12 illustrates an example heat pipe1204. The heat pipe 1204 is hollow and has an evaporator 1202 located ona top surface 1210, a vapor portion 1206, and a condenser 1208 locatedwon a bottom surface 1212. The evaporator 1202 is connected to the heatsource (e.g., the power devices 202). The evaporator contains liquidthat is heated by the heat source. The heated liquid is vaporized by theheat and heated vapor travels through the vapor portion 1206 to thecondenser 1208.

The heated vapor cools as it contacts the condenser 1208. The cooledvapor condenses on the interior walls of the condenser 1208 and turns toliquid. The liquid travels back to the evaporator 1202, where theprocess will be repeated. The heating, vaporization, cooling, andcondensing of the liquid in the heat pipe 1204 is an efficient way toprovide cooling to the heat source.

FIG. 13 illustrates a cross-sectional view of a vapor chamber 1304 usingsimilar principles as the heat pipe 1204. The evaporator 1302 of thevapor chamber 1304 receives heat 1322 from a heat source (e.g., powerdevices 202) via a first plate 1336 and a second plate 1338. The heat1322 heats and vaporizes liquid in the vapor chamber 1304, resulting invapor generation 1330. The vapor flows to the center of the vaporchamber 1304 and travels 1340 along the adiabatic section 1334. Thevapor condenses 1332 as the heat is released 1324 along the first plate1336 and the second plate 1338 in the condenser 1308. The condensation1332 is absorbed by a wick 1328 lining the interior walls of the vaporchamber 1304. The condensed vapor turns to liquid and returns 1326 to anarea near the evaporator 1302, and the process continues.

FIGS. 14A and 14B illustrate an O lead frame 1404 with an integratedvapor chamber similar to heat pipe 1204 and vapor chamber 1304. FIG. 14Ais a side view of the power card with the O lead frame 1404 and FIG. 14Bis a top view of the power card with the O lead frame 1404.

As shown in FIG. 14A, the O lead frame 1404 includes a body portion 1406and a cooling portion 1408 extending from the body portion 1406. The Olead frame 1404 has an interior cavity. The body portion 1406 includesan evaporator 1402 and the cooling portion 1408 includes a condenser1418. Lining the interior cavity of the O lead frame 1404 is a wick1422. The evaporator 1402 and the condenser 1418 are in fluidcommunication.

The power devices 202A and 202B, which are coupled to the body portion1406 of the O lead frame 1404, heat liquid within the evaporator 1402and the liquid vaporizes. The vapor 1420 moves to the condenser 1418 ofthe cooling portion 1408. The vapor 1420 cools as heat from the vapor isdissipated by the walls of the condenser 1418 and the vapor condensesinto a liquid along one or more interior surfaces of the condenser 1418.The condensed vapor (now a liquid) is absorbed by the wick 1422 andreturned to the evaporator 1402. The process repeats and allows the Olead frame 1404 to provide cooling to the power devices 202A and 202B.

FIG. 14B illustrates the vapor flow 1410 of the vapor 1420 moving fromthe evaporator 1402 to the condenser chamber 1418 of the cooling portion1408.

FIG. 15 illustrates an O lead frame 1504 having a body portion 1506 andmultiple cooling portions 1508 extending from the body portion 1506. Inparticular, a first cooling portion 1508A extends along the length ofthe power card that the O lead frame 1504 is used in. A second coolingportion 1508B extends in a first side direction along the width of thepower card. A third cooling portion 1508C extends in a second sidedirection along the width of the power card. Thus, the second coolingportion 1508B and the third cooling portion 1508C may be on oppositesides of the O lead frame 1504, and may each extend in directionsperpendicular to the direction the first cooling portion 1508A extendsin.

The body portion 1506 includes an evaporator 1502 similar to evaporator1402. The cooling portions 1508 each include respective condensers 1518for cooling the vapor created by the heat from the power devices thatare coupled to the body portion 1506. In particular, the first coolingportion 1508A has a first condenser 1518A, the second cooling portion15088 has a second condenser 15188, and the third cooling portion 1508Chas a third condenser 1518C. Each condenser 1518 is fluidly coupled tothe evaporator 1502 to receive vapor from the evaporator and to sendcondensed liquid via an internal wick (e.g., wick 1422).

The additional cooling portions of the O lead frame 1504, as compared tothe O lead frame 1404, may allow the O lead frame 1504 to moreefficiently dissipate heat generated by the power devices. The O leadframe 1504 may be used with power cards that do not have a set of signalterminals on the side of the power card, such as power card 200illustrated in FIG. 2F. While three discrete cooling portions areillustrated in FIG. 15, in some embodiments, there may be more coolingportions (e.g., 6 cooling portions, 9 cooling portions, etc.) or theremay be one continuous cooling portion spanning a perimeter of the O leadframe 1504 on three sides of the body portion 1506.

In some embodiments, the cooling portions 808, 1108, 1408, 1508 may bereferred to as terminal portions. In some embodiments, any of the O leadframes described herein may be made of a material having high thermalconductivity in two axes, but low thermal conductivity along a thirdaxis, for improving the cooling capabilities of the O lead frame. Exceptas noted herein, any of the components of any embodiment describedherein may be used with any other embodiment. The embodiments describedand illustrated are non-limiting.

FIG. 16 illustrates a process 1600 for fabricating a power card (e.g.,power card 200, 500, 800) described herein. An N lead frame (e.g., Nlead frame 206) is fabricated (step 1602). The N lead frame has a bodyportion (e.g., body portion 232) and a terminal portion (e.g., terminalportion 226) extending outward from the body portion. The N lead framemay be fabricated by stamping, etching, casting, or any other method forfabricating lead frames. The N lead frame may be made of a conductivematerial, such as copper or an alloy of copper.

A P lead frame (e.g., P lead frame 208) is fabricated (step 1604). The Plead frame has a body portion (e.g., body portion 230) and a terminalportion (e.g., terminal portion 224) extending outward from the bodyportion. The P lead frame may be fabricated by stamping, etching,casting, or any other method for fabricating lead frames. The P leadframe may be made of a conductive material, such as copper or an alloyof copper.

An O lead frame (e.g., O lead frame 204, 504, 604, 704, 804, 1104, 1404,1504) is fabricated (step 1606). The O lead frame has a body portion(e.g., body portion 228) and a terminal portion (e.g., terminal portion222) extending outward from the body portion. In some embodiments, the Olead frame has one or more cooling portions (e.g., cooling portion 808,1108, 1408, 1508) extending outward from the body portion instead of aterminal portion. The O lead frame may be fabricated by stamping,etching, casting, soldering, molding, or any other method forfabricating lead frames. The O lead frame may be made of a conductivematerial, such as copper or an alloy of copper.

A first power device (e.g., power device 202) is coupled to the bodyportion of the N lead frame and the body portion of the O lead frame(step 1608). The first power device may have a first side (e.g., firstside 480) coupled to the body portion of the N lead frame. The firstpower device may have a second side (e.g., second side 482) coupled tothe body portion of the O lead frame.

A second power device (e.g., power device 202) is coupled to the bodyportion of the O lead frame and the body portion of the P lead frame(step 1610). The second power device may have a first side (e.g., firstside 480) coupled to the body portion of the O lead frame. The secondpower device may have a second side (e.g., second side 482) coupled tothe body portion of the P lead frame.

Solder may be located between the components of the power card, andreflow soldering may be used to connect the respective components of thepower card together, as described herein.

The N lead frame, the O lead frame, and the P lead frame may be orientedsuch that the terminal portion of the O lead frame is at a first end ofthe power card and the terminal portion of the P lead frame and theterminal portion of the N lead frame are at a second end of the powercard.

An insulator may be disposed between the terminal portion of the P leadframe and the terminal portion of the N lead frame. A first signalterminal may be connected to the first power device using solder balls,and a second signal terminal may be connected to the second power deviceusing solder balls.

The resin (e.g., resin 210) may encase a portion of the power card. Theresin may be injection molded to the power card such that all gapsbetween the components of the power card are occupied with resin. Theterminal portion of the O lead frame, portions of the sets of signalterminals, a portion of the terminal portion of the P lead frame, and aportion of the terminal portion of the N lead frame may not be coveredin resin, with the remaining components of the power card being encasedin resin. The exposed portion of the terminal portion of the P leadframe may be the top surface of the terminal portion. The exposedportion of the terminal portion of the N lead frame may be the bottomsurface of the terminal portion.

The cooling portions (e.g., cooling portion 808, 1108, 1408, 1508) mayalso be terminal portions of their respective O lead frames, configuredto provide an output signal, as described herein.

Exemplary embodiments of the methods/systems have been disclosed in anillustrative style. Accordingly, the terminology employed throughoutshould be read in a non-limiting manner. Although minor modifications tothe teachings herein will occur to those well versed in the art, itshall be understood that what is intended to be circumscribed within thescope of the patent warranted hereon are all such embodiments thatreasonably fall within the scope of the advancement to the art herebycontributed, and that that scope shall not be restricted, except inlight of the appended claims and their equivalents.

What is claimed is:
 1. A power card for use in a vehicle, the power cardcomprising: an N lead frame having a body portion and a terminalportion, the terminal portion extending outward from the body portion; aP lead frame having a body portion and a terminal portion, the terminalportion extending outward from the body portion; an O lead frame havinga body portion and a cooling portion, the cooling portion extendingoutward from the body portion, the O lead frame being located betweenthe N lead frame and the P lead frame and the body portion of the P leadframe and the body portion of the N lead frame are non-overlapping withthe cooling portion of the O lead frame; a first power device beinglocated on a first side of the O lead frame between the body portion ofthe N lead frame and the body portion of the O lead frame; and a secondpower device being located on a second side of the O lead frame betweenthe body portion of the O lead frame and the body portion of the P leadframe, the O lead frame configured to receive heat from the first powerdevice and the second power device by the body portion of the O leadframe and transfer the heat to the cooling portion of the O lead framefor heat dissipation.
 2. The power card of claim 1, wherein the O leadframe is made of a material having a higher thermal conductivity along afirst axis and a second axis than along a third axis, the first axis,second axis, and third axis being perpendicular to each other.
 3. Thepower card of claim 2, wherein the first axis is a vertical axis, thesecond is a lengthwise axis, and the third axis is a widthwise axis. 4.The power card of claim 2, wherein the material is graphite.
 5. Thepower card of claim 1, further comprising a first end and a second end,the second end being opposite the first end, and wherein the coolingportion of the O lead frame is at the first end and the terminal portionof the P lead frame and the terminal portion of the N lead frame are atthe second end.
 6. The power card of claim 1, further comprising aplatform coupled to the body portion of the O lead frame and having afirst side configured to couple to the first power device and a secondside configured to couple to the second power device, and wherein theplatform is made of a material having a lower thermal conductivity thanthe body portion of the O lead frame along a vertical axis.
 7. The powercard of claim 1, wherein the body portion of the O lead frame includesan evaporator and the cooling portion of the O lead frame includes acondenser, the evaporator and the condenser being in fluidcommunication, the evaporator configured to convert liquid locatedwithin the evaporator to vapor using the heat received from the firstpower device and the second power device, and the condenser configuredto receive the vapor and convert the vapor to liquid along one or moresurfaces of the condenser, the liquid being returned to the evaporator.8. The power card of claim 7, further comprising a wick located along aninterior surface of the evaporator and the condenser, the wickconfigured to absorb the condensed liquid in the condenser and returnthe condensed liquid to the evaporator.
 9. A power system comprising: apower card having: an O lead frame located between an N lead frame and aP lead frame, the O lead frame having a body portion and a coolingportion, the cooling portion extending from the body portion such that abody portion of the P lead frame and a body portion of the N lead frameare non-overlapping with the cooling portion, a first power devicelocated on a first side of the O lead frame between the N lead frame andthe O lead frame, and a second power device located on a second side ofthe O lead frame between the O lead frame and the P lead frame, the Olead frame configured to receive heat from the first power device andthe second power device by the body portion of the O lead frame andtransfer the heat to the cooling portion of the O lead frame for heatdissipation.
 10. The power system of claim 9, wherein the O lead frameis made of a material having a higher thermal conductivity along a firstaxis and a second axis than along a third axis, the first axis, secondaxis, and third axis being perpendicular to each other.
 11. The powersystem of claim 10, wherein the first axis is a vertical axis, thesecond is a lengthwise axis, and the third axis is a widthwise axis. 12.The power system of claim 10, wherein the material is graphite.
 13. Thepower system of claim 9, further comprising a first end and a secondend, the second end being opposite the first end, and wherein thecooling portion of the O lead frame is at the first end and the terminalportion of the P lead frame and the terminal portion of the N lead frameare at the second end.
 14. The power system of claim 9, furthercomprising a platform coupled to the body portion of the O lead frameand having a first side configured to couple to the first power deviceand a second side configured to couple to the second power device, andwherein the platform is made of a material having a lower thermalconductivity than the body portion of the O lead frame.
 15. The powersystem of claim 9, wherein the body portion of the O lead frame includesan evaporator and the cooling portion of the O lead frame includes acondenser, the evaporator and the condenser being in fluidcommunication, the evaporator configured to convert liquid locatedwithin the evaporator to vapor using the heat received from the firstpower device and the second power device, and the condenser configuredto receive the vapor and convert the vapor to liquid along one or moresurfaces of the condenser, the liquid being returned to the evaporator.16. A lead frame for use in a vehicle power card, the lead framecomprising: a body portion having a first side coupled to a first powerdevice, a second side coupled to a second power device, and anevaporator, the body portion being configured to absorb heat from thefirst power device and the second power device, and the evaporatorconfigured to convert liquid located within the evaporator to vaporusing the heat received from the first power device and the second powerdevice; and a cooling portion having a condenser in fluid communicationwith the evaporator, the cooling portion extending outward from the bodyportion and configured to receive the absorbed heat from the bodyportion for heat dissipation, and the condenser configured to receivethe vapor and convert the vapor to liquid along one or more surfaces ofthe condenser, the liquid being returned to the evaporator.
 17. The leadframe of claim 16, wherein the body portion and the cooling portion aremade of a material having a higher thermal conductivity along a firstaxis and a second axis than along a third axis, the first axis, secondaxis, and third axis being perpendicular to each other.